Personality Characteristics in Obesity

ORIGINAL ARTICLE

Personality characteristics in obesity and relationshipwith successful weight loss

S Sullivan1, CR Cloninger2, TR Przybeck2 and S Klein1

1Department of Internal Medicine, Center for Human Nutrition, Washington University School of Medicine, St Louis, MO,USA and 2Department of Psychiatry, Center for Human Nutrition, Washington University School of Medicine, St Louis, MO,USA

Objective: Personality influences lifestyle behaviors. Therefore, certain personality traits could contribute to obesity and theresponse to behaviorally based weight loss therapy.Purpose: The aims of this study were to test the hypothesis that personality characteristics differ between lean and obesepersons in the community, obese persons in the community and obese persons seeking weight loss therapy by enrolling in acomprehensive weight loss program, and in obese persons who were successful and unsuccessful in achieving behavioraltherapy-induced weight loss.Methods: The Temperament and Character Inventory was administered to 264 lean (body mass index (BMI) o25 kg/m2) and56 obese (BMIX35 kg/m2) subjects from the St Louis community and 183 obese patients (BMI¼ 44710 kg/m2) enrolled in theWashington University Weight Management Program (WUWMP), which involved weekly group behavioral therapy and dieteducation sessions for 22 weeks.Results: Compared with lean subjects, obese subjects in the community scored higher in novelty seeking (19.775.9 vs16.276.0, Po0.05), lower in Persistence (4.171.8 vs 4.871.7, Po0.05) and lower in self-directedness (32.177.6 vs34.376.6, Po0.05.) Patients enrolled in the WUWMP scored higher than obese persons in the general population in bothReward Dependence (17.174.2 vs 15.774.3, Po0.05) and cooperativeness (36.975.4 vs 34.576.2, Po0.05). Patients whowere successful in losing weight (410% weight loss) after 22 weeks of behavioral therapy scored lower in novelty seeking thanthose who were unsuccessful in losing weight (o5% weight loss) (17.675.9 vs 20.275.9, Po0.05).Discussion: These results suggest that personality traits differ between lean and obese persons, and between obese persons whoenroll and who do not enroll in a comprehensive weight management program. Moreover, high scores in novelty seeking areassociated with decreased success in achieving behavioral therapy-induced weight loss.

International Journal of Obesity (2007) 31, 669–674. doi:10.1038/sj.ijo.0803464; published online 5 September 2006

Keywords: personality; temperament; character; behavior modification

Introduction

Data from the most recent Nutrition and Health Examina-

tion Survey demonstrate that the prevalence of obesity

remains a problem in both children and adults in the United

States.1 Although approximately 45% of women and 30%

of men are trying to lose weight,2 weight loss is difficult to

achieve, and even those who lose weight often regain lost

weight over time.3 Heritable personality traits can influence

dietary intake4 and could be involved in the susceptibility to

obesity and in the failure of obese persons to achieve

successful weight loss. Several studies have evaluated the

relationship between personality traits, assessed by the

Karolinska Scales of Personality (KSP), and weight loss

outcome in obese persons trying to lose weight.5–11 However,

the results from these studies are inconsistent, possibly

because of limitations in the KSP, which was designed to

evaluate abnormal personality, rather than variations in

normal personality.12,13

Recently, a new questionnaire, the Temperament and

Character Inventory (TCI), was developed to provide a

comprehensive evaluation of personality.14–16 The TCI

measures seven dimensions of personality: (1) novelty

seeking, (2) reward dependence, (3) harm avoidance, (4)

persistence, (5) self-directedness, (6) self-transcendence

and (7) cooperativeness. Each dimension has a unique

genetic variance and is reproducible in clinical and generalReceived 24 April 2006; revised 28 June 2006; accepted 14 July 2006;

published online 5 September 2006

Correspondence: Dr S Klein, Department of Internal Medicine, Washington

University School of Medicine, 660 S. Euclid Avenue, Box 8031, St Louis, MO

63110, USA.

E-mail: [email protected]

International Journal of Obesity (2007) 31, 669–674& 2007 Nature Publishing Group All rights reserved 0307-0565/07 $30.00

www.nature.com/ijo

populations.14,16 By using the TCI, distinct personality

characteristics were identified in patients who have eating

disorders, such as bulimia, anorexia nervosa and binge

eating disorder. For example, a high score in novelty seeking

was associated with binging or overeating, whereas a low

score was associated with a low appetite and decreased food

consumption.17–22 Moreover, the TCI was able to identify

specific components of personality that were associated

with a rapid and sustained response to cognitive behavioral

therapy for bulimia.23

The purpose of the present study was to use the TCI to (1)

identify differences in personality characteristics between

lean and obese persons, (2) determine whether personality

characteristics in obese patients seeking weight loss therapy

are different from those not seeking weight loss therapy and

(3) determine whether specific components of personality

are associated with successful behavioral therapy-induced

weight loss.

Methods

Subjects

A total of 503 adults participated in this study. The subjects

included a community sample of 264 lean (body mass

index (BMI) 18.5–24.9 kg/m2) and 56 class II and III obese

(BMIX35 kg/m2) persons identified by random sampling

from a standard telephone listing of residents in the St Louis

greater metropolitan area, and a patient sample of 183 obese

persons (BMIX30 kg/m2) enrolled in the Washington Uni-

versity Weight Management Program (WUWMP) (Table 1).

Subjects gave informed consent before participating in this

study, which was approved by the Human Studies Commit-

tee of Washington University School of Medicine.

Study protocol

The community sample of lean and obese subjects was

obtained from a group of 629 men and women, living in

the St Louis, Missouri metropolitan area, who participated

in two surveys of personality, health and lifestyle. These

surveys involved completing mailed questionnaires, 1 year

apart.24,25 The second survey included the TCI, information

on height and weight, and was used to provide the data for

our study. Of these 629 subjects, 320 met the BMI inclusion

criteria for the present study and were included as our

community sample.

The patient sample consisted of obese persons who were

actively involved in obesity treatment at the WUWMP. A total

of 187 obese persons attended informational sessions between

March 1998 and June 2000 to learn about the WUWMP; all

persons completed the TCI questionnaire. Of these 187

attendees, 183 (98%) enrolled in the WUWMP. All 183

subjects completed at least 3 weeks of the 22-week program,

and 131 (70%) completed the entire 22-week program. All

subjects who completed at least 3 weeks of the program were

included in an intention-to-treat analysis. The weight loss

program involved weekly group behavior modification ses-

sions, nutrition seminars, physical activity education and

medical monitoring. Each subject was provided instructions

for a 1000 kcal/day deficit diet, which included meal replace-

ments consisting of shakes, snack bars and commercially

prepared meal entrees. Height and weight was measured at

the initial visit and body weight was recorded weekly.

Personality assessment

The TCI is a 240-question instrument, which measures four

dimensions of temperament (novelty seeking, harm avoid-

ance, reward dependence and persistence) and three dimen-

sions of character (self-directedness, cooperativeness and

self-transcendence) (Table 2).14,16 Temperaments are aspects

of emotional responses and are stable through time, whereas

characters are styles of mental self-government and may

develop or mature through time. The test is written at a

Flesch–Kincaid grade level¼3.4 (very easy). The question-

naire is composed of a series of true/false questions about the

test taker’s likes and dislikes, emotional reactions, interests,

attitudes, goals and values, which is then scored to assess the

different dimensions of personality. Each of the seven

dimensions is uniquely heritable and associated with specific

neurotransmitter genes and regional brain activity.24 The

internal consistency of the TCI measurements range from

0.76 to 0.89.14,16 The TCI scales are approximately normally

distributed.14

Statistical analysis

A Student’s t-test for independent samples was used to

determine the statistical significance of differences between

lean and obese subjects in the general population, obese

subjects (BMIX35 kg/m2) enrolled and not enrolled in a

weight management program, and the TCI characteristics

associated with successful (410% weight loss) and unsuc-

cessful (o5% weight loss) weight loss. The criteria for

successful and unsuccessful weight loss were defined by

the amount of weight loss (i.e. X10% weight loss) that is

Table 1 Characteristics of the study subjects

Community

lean

Community

obese

WUWMP

obese

Total number 264 56 183

Male 95 23 41

Female 169 33 142

Age (years) 46.0717.8 46.5714.3 45.1710.4

BMI (kg/m2) 22.271.8 40.776.5 44.6710.3

BMI 30.0–34.9 kg/m2 (no.) 0 0 25

BMI 435.0 kg/m2 (no.) 0 56 158

Abbreviations: BMI, body mass index; WUWMP, Washington University

Weight Management Program.

Personality characteristics in obesity and successful weight lossS Sullivan et al

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International Journal of Obesity

associated with significant improvements in obesity-related

medical complications and is the target goal for patients who

enroll in our weight management program, and the amount

of weight loss (i.e. o5% weight loss) that does not usually

result in significant medical benefits. Data were analyzed

by using SAS v6.12. A P-value p0.05 was considered to be

statistically significant. F-tests were used to confirm that the

homogeneity of variance assumption of the t-tests was met.

All values are reported as mean7s.d.

Power calculations were performed for the three compa-

risons to detect a difference at the 0.05 level with a power of

80%. The critical effect size for comparing lean subjects and

obese subjects in the general population was 0.17 of the s.d.,

for obese subjects in the general population and obese

patients enrolled in the WUWMC was 0.22 of the s.d. and

for patients enrolled in the WUWMC who were successful

at weight loss and those who were not was 0.34 of the s.d.

Results

Lean and obese personality characteristics

In the general population, residing in the greater St Louis

metropolitan area, obese subjects (BMIX35.0 kg/m2) had

significantly higher novelty seeking (effect size 0.58) and

lower persistence and self-directedness scores than lean

subjects (BMI o25.0 kg/m2) (Table 3). There was a trend

toward decreased reward dependence and cooperativeness in

obese than lean subjects, but the differences between groups

was not statistically significant.

Obese enrolled and not enrolled in weight loss treatment

Obese subjects enrolled in treatment had significantly higher

scores for reward dependence and cooperativeness than

obese subjects in the general population (Table 4). Scores for

novelty seeking, harm avoidance, self-directedness and self-

transcendence were not significantly different between obese

subjects enrolled and not enrolled in weight loss therapy.

Table 2 Characteristics of personality dimensions assessed by the tempera-

ment and character inventory

Personality

dimension

High scorers Low scorers

Temperament

Harm avoidance Worrying and

pessimistic

Relaxed and optimistic

Fearful and doubtful Bold and confident

Shy Outgoing

Fatigable Vigorous

Novelty seeking Exploratory and curious Indifferent

Impulsive Reflective

Extravagant and

enthusiastic

Frugal and detached

Disorderly Orderly and regimented

Reward

dependence

Sentimental and warm Practical and cold

Dedicated and attached Withdrawn and detached

Dependent Independent

Persistence Industrious and diligent Inactive and indolent

Hard-working Gives up easily

Ambitious and

overachiever

Modest and underachiever

Perseverant and

perfectionist

Quitting and pragmatist

Character

Self-directedness Mature and strong Immature and fragile

Responsible and reliable Blaming and unreliable

Purposeful Purposeless

Resourceful and effective Inert and ineffective

Self-accepted Self-striving

Habits congruent with

long-term goals

Habits incongruent with

long-term goals

Cooperativeness Socially tolerant Socially intolerant

Empathetic Critical

Helpful Unhelpful

Compassionate and

constructive

Revengeful and destructive

Ethical and principled Opportunistic

Self-transcendence Wise and patient Impatient

Creative and

self-forgetful

Unimaginative and

self-conscious

United with universe Pride and lack of humility

Table 3 Personality characteristics in lean (BMIo25.0 kg/m2) and obese

(BMIX35.0 kg/m2) persons in the general population

Personality dimension Lean (n¼264) Obese (n¼56)

Novelty seeking 16.276.0 19.775.9*

Harm avoidance 13.377.3 14.777.5

Reward dependence 16.874.0 15.774.3

Persistence 4.871.7 4.171.8**

Self-directedness 34.376.6 32.177.6#

Cooperativeness 35.975.2 34.576.2

Self-transcendence 15.376.3 15.276.3

Abbreviations: BMI, body mass index. Values significantly different from lean

persons in the community value, *Po0.001, **Po0.005, #P¼ 0.02.

Table 4 Personality characteristics in obese persons (BMI X35 kg/m2) in the

community and obese persons (BMI X35 kg/m2) enrolled in the WUWMP

Personality

dimension

Obese persons in

the community

(n¼ 56)

Obese persons

enrolled in weight

loss therapy

(n¼ 158)

Novelty seeking 19.775.9 19.275.9


Reward dependence 15.774.3 17.174.2*

Self-directedness 32.077.5 31.078.7

Cooperativeness 34.576.2 36.975.4**


Abbreviations: BMI, body mass index; WUWMP, Washington University

Weight Management Program. Value significantly different than correspond-

ing. Obese persons in the community value, *Po0.05, **P¼ 0.01.


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Persistence was not included in the final comparison

between obese in the community and obese at the WUWMP,

because the persistence scale in the TCI was modified after

it was given to the subjects in the general populations.

Therefore, a direct comparison cannot be made.

Personality and weight loss outcome

Obese subjects who were successful in achieving X10% of

their initial weight had lower scores for novelty seeking than

obese subjects who lost o5% of their initial body weight

after 22 weeks of weight loss therapy (Table 5). Scores for

the other dimensions of personality were not significantly

different between successful and unsuccessful subjects.

Discussion

This study represents the first use of the TCI to evaluate

personality characteristics in obese persons in the general

population, and those enrolled in a comprehensive weight

management program. The TCI has advantages over other

measures of personality, because it provides a reproducible

assessment of normal variations in personality. The major

findings of the present study are that (1) obese persons have

higher novelty seeking but lower persistence and self-

directedness traits than lean persons in the general popula-

tion, (2) obese persons enrolled in a comprehensive weight

management program have higher reward dependence and

cooperativeness than those in the general population and (3)

obese persons who are successful at achieving initial weight

loss have a lower novelty seeking trait than those who are

not successful. These data suggest that specific personality

characteristics are involved in the pathogenesis of obesity,

and might help identify persons who are likely to respond to

an obesity treatment program that includes comprehensive

behavioral therapy.

We found that the score for novelty seeking temperament

was higher in obese than lean subjects sampled from the

general population. People who score high in novelty

seeking tend to be thrill seekers, are easily bored, impulsive

and try to avoid monotony. Therefore, these data suggest

that overeating to avoid boredom might contribute to

obesity. The results from our study are consistent with the

results from previous studies, which found healthy dietary

control and cognitive control of food intake are associated

with lower scores in novelty seeking and obesity is associated

with high reinforcement value associated with eating.7,22,26

Although data from some studies found that impulsiveness

and monotony avoidance, assessed by the KSP scale, are

higher in an obese population than a reference popula-

tion,5,8 others have found that subjects who scored high in

monotony avoidance were less likely to exhibit disinhibited

eating behaviors in social situations,6 suggesting that

environmental situations can influence the expression of

personality characteristics.

Our community obese population also scored lower in self-

directedness than lean persons. Self-directedness is a measure

of internal organization, and the ability to set and pursue

meaningful goals.16 Therefore, these data suggest that obese

people may have a decreased ability to set weight loss goals

and to maintain behaviors that lead to weight control.

Conversely, patients with anorexia nervosa score high in

persistence and have very strict and rigid patterns of food

intake.17–21

Obese persons who sought treatment at our weight

management program scored higher in reward dependence

and cooperativeness than our sample of obese persons from

the community. These personality characteristics are found

in people who tend to be dedicated and sociable (high

reward dependence score), tolerant, fair and supportive

(high cooperativeness score). It is likely that our weight

management program, which involves group behavior

therapy and requires a considerable commitment from

patients, attracted obese persons with these personality

traits. Therefore, patients enrolled in our program, and

presumably those who choose to enroll in other rigorous

weight loss programs, represent a select subset of obese

persons who are more likely to comply with treatment than

other obese persons in the community. These results suggest

that data reported from weight loss trials that are conducted

in volunteers who chose to participate will generate more

optimistic weight loss results than if therapy were initiated

in the community.

Patients enrolled in our weight management program who

were successful at losing weight had lower novelty seeking

scores than those who did not achieve successful weight loss.

These results imply that obese persons who may eat to

combat boredom have considerable difficulty losing weight

with standard behavior modification therapy. Similarly, data

from previous studies have shown that obese people who

scored high in the KSP scale of impulsivity lost less weight in

a weight management program than those with lower

scores,6 and that monotony avoidance was associated with

difficulty in maintaining weight loss after jaw fixation.9,10

In contrast, Walker et al.11 found that only monotony

Table 5 Personality scores in successful (X10% weight loss) and unsuccess-

ful (o5% weight loss) obese subjects enrolled in the WUWMP

Personality

dimension

Unsuccessful

obese subjects

(n¼52)

Successful

obese subjects

(n¼69)

Novelty seeking 20.275.9 17.675.9*


Reward dependence 17.374.0 16.774.4

Persistence 5.171.8 5.572.0

Self-directedness 30.379.7 32.178.6

Cooperativeness 36.175.1 36.975.8


Abbreviation: WUWMP, Washington University Weight Management Pro-

gram. Value significantly different from corresponding unsuccessful obese

subjects value, *P¼0.02.


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Esto es lo que pone de manifiesto la necesidad de acompañar cualquier intento de baja de peso de tipo nutricional, con una terapia psicológica. Ya que la patogenia de la obesidad está en las características de personalidad.

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Características asociadas al rasgo de personalidad "Curiosidad"

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avoidance was not associated with initial weight loss, and

was only weakly associated with 12-month weight relapse.

However, in that study, the initial weight management

program was only 8 weeks long, and it is possible that

treatment needs to be longer to see differences in weight loss

between high and low scorers in novelty seeking.

The number of subjects who participated in this study was

sufficiently large to detect even weak effects of personality

on obesity, treatment seeking behavior and success in

treatment (effect sizes between 0.17 and 0.34). The effects

we observed were very strong and identified important

differences in personality characteristics between groups.

Specifically, novelty seeking personality trait was strongly

associated with obesity in the general population (effect size

0.58), and reduced the likelihood of successful weight loss

treatment outcome (effect size 0.44). These data suggest that

high novelty seeking scores indicate a strong appetitive

drive. Reward dependence was strongly associated with

treatment seeking behavior, consistent with the notion that

high reward dependence indicates a need for social approval.

The effects of persistence and cooperativeness on the risk of

being obese and seeking obesity treatment were moderate

(effect sizes of 0.41–0.44).

In summary, the results of the present study demonstrate

differences in selected personality characteristics between

lean and obese persons, obese persons in the general

population and those who enrolled in a rigorous weight loss

program, and obese persons who are successful and those

who are unsuccessful at losing weight with group behavior

therapy. These data underscore the future potential useful-

ness of personality assessment in obesity management.

Additional studies are needed to determine whether person-

ality characteristics can be used to identify patients, in

advance, who can benefit from behavioral weight loss

therapy, whether personality characteristics change after

weight loss in a program that includes behavior modification

and finally, whether outcome can be improved by modifying

therapy based on individual personality traits.

Acknowledgements

We thank Shane Cotter and the staff of the Washington

University Weight Management Program for their assistance,

and the study subjects for their participation.This study was

supported by National Institutes of Health Grants MH60879

and DK 56341.

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Personality Characteristics in Obesity